This invention relates to door latching mechanisms and particularly, but not exclusively, to door latching mechanisms for the door of an enclosure for housing electronic equipment and electrical cabling and associated equipment.
The doors of such enclosures generally comprise a metal panel with a reinforced edge section to provide rigidity to the door, and the edge section is desirably a box-section.
It is desirable that a latching mechanism is provided which is engaged on slamming shut the door, and we consider it desirable that the latching mechanism should be capable of being housed substantially within the reinforced edge section extending along one vertical edge of the door.
This means that any moving parts of the mechanism are unlikely to come into contact with any cabling housed within the enclosure.
According to one aspect of the invention a door latching mechanism comprises two oppositely-directed, vertically-slidable rods adapted to engage at their outer ends respectively with the top and bottom of a door frame, and a main latch member adapted to engage with a keeper provided on or in the side of the door frame, the latching mechanism comprising a push rod actuating assembly which is connected between the inner ends of the push rods and is engaged by the main latch member, and is so arranged, in use, to urge the push rods in opposite outward directions on latching engagement of the main latch member with the door side frame, the push rod actuating assembly comprising an actuating assembly housing in or on which is mounted first and second gear pinions that are respectively meshed with vertically slidable oppositely-directed push rod bars connected to the respective inner ends of the push rods, the pinions being meshed with respective racks provided on opposite sides of a slider which is slidable substantially horizontally relative to the housing, the main latch member connecting with the slider whereby on release of the main latch member from the keeper, the slider is moved to draw the push rods towards one another.
According to a second aspect of the invention we provide a push rod actuating assembly suitable for use in a door latching mechanism in accordance with the first aspect of the invention, the actuating assembly comprising an actuating assembly housing in or on which is mounted first and second gear pinions that are respectively meshed with slidable oppositely-directed push rod bars adapted to be connected in use at their outer ends to the respective inner ends of a pair of oppositely-directed push rods, the pinions being meshed with respective racks provided on opposite sides of a slider which is slidable substantially transversely of the direction of sliding movement of the push rod bars, the slider being adapted to be operable by a connection from a main door latching member.
The push rod actuating assembly substantially counterbalances the weight of the upper push rod by that of the lower push rod, whereby only frictional forces need to be overcome in urging the push rods outwardly so that a reduced slamming force is required to provide an effective three-point locking action of the door to the door frame.
The two push rods, which may be of any convenient cross-section such as oblong-rectangular, are preferably axially aligned with one another so as to slide along a common axis.
The push rod actuating assembly preferably comprises resilient means which acts so as to urge the push rod bars in opposite directions apart.
Although the resilient means may be associated with the slider, preferably the resilient means comprises a tension spring connected between spring anchors provided on the respective pinions, and conveniently the pinions each comprise a toothless portion to accommodate the spring anchors.
The slider is preferably provided with an aperture to receive a connection from the main latch member, the housing containing one or more corresponding access apertures.
Preferably the housing is of substantially rectangular shallow box shape, and opposite side walls of the housing are provided with said access apertures to enable said connections to extend through the housing and slider.